1. Field of the Invention
The present invention relates to a recording apparatus for performing recording on an optical disc recording medium which has a plurality of recording layers and is capable of having data rewritten thereon. The present invention also relates to a recording method for the recording apparatus.
2. Description of the Related Art
Optical disc recording media are known examples of optical recording media capable of having information optically recorded thereon and reproduced therefrom.
As an example of such recording media, DVDs (Digital Versatile Discs) are widely used. Types of existing DVDs include reproduction-only DVD-ROMs on which information is recorded in the form of combinations of embossed pits and lands, DVD-Rs or DVD+Rs in which dye-change films are used for the recording layers, which permits recording to be performed only one time, and DVD-RWs or DVD+RWs in which phase-change films are used for the recording layers, thereby allowing rewriting of data.
Among the above DVDS, DVD+RWS, as a type of rewritable medium, were developed later than DVD-RWs which are also a type of rewritable medium. Therefore, DVD+RWs are provided with increased user operability compared with DVD-RWs.
For example, for DVD+RWs, an arrangement is employed which enables reduction of time necessary for disc formatting.
A rewritable disc such as a DVD+RW disc is configured to undergo a so-called formatting process so as to be usable in a reproduction-only apparatus. In such a formatting process, an unrecorded part of a data area intended for recording of user data is filled with dummy data such as all 0 data.
For some types of discs, such a formatting process for ensuring compatibility with reproduction apparatuses is performed on the entire disc prior to recording of user data. In contrast, DVD+RW discs are configured to allow user data recording to be started without disc formatting, which reduces preparation time for recording. In this case, disc formatting for an unrecorded part is configured to proceed automatically while no writing or reading operation is being performed in a drive (idling state). Thus, the formatting process progresses in the background, enabling reduction of user waiting time and thus enhancing operability. Such a formatting technique described above is called background formatting.
For a DVD+RW disc, the entire disc is not to be formatted immediately after disc loading. Therefore, there may be a case where the disc, in which only a part of its data area is recorded with user data, is requested before formatting of the entire disc is not completed.
When such a recorded disc which is partially formatted is ejected, a temporary lead-out is added at the end of a region recorded with the user data. This operation ensures compatibility with a reproduction-only apparatus.
Thus, providing a lead-out area in a data area enables reproduction of the recorded user data in a reproduction-only apparatus. Since such a lead-out area is temporary, recording of user data can be restarted by erasing the lead-out area when the disc is loaded again.
Such background formatting performed for a DVD+RW disc in connection with addition of temporary lead-out will be described with reference to FIG. 9, FIG. 10A and FIG. 10B.
Each of these figures illustrates an area structure of a disc. As shown in the figures, a lead-in area is located at the innermost radius of the disc, followed by a data area intended for user data recording which is located at the outer radius side of the lead-in area.
Referring now to FIG. 9, a condition of the disc is illustrated by way of example, in which a data file has been recorded. When such a data file is recorded on the disc, it is highly likely that the data file is recorded in the form of user data blocks (UDs) which are recorded intermittently in the data area as shown in FIG. 9. Particularly in a case where a UDF (Universal Disc Format) is used for the disc, the recording operation is carried out in such a manner that file management information is recorded as a user data block UD 1 at the innermost radius side of the data area which immediately follows the lead-in area. In this operation, a data file of actual data is not necessarily recorded at the region adjacent to the region where the file management information is recorded. Therefore, it is highly likely that the user data block UD 1 recorded at the innermost radius of the data area and user data UD 2 which serves as the actual data are recorded having a space therebetween.
In this condition in which data blocks have been intermittently recorded, the data area contains an unrecorded part and is not provided with a lead-out area. This leaves the disc incompatible with reproduction-only apparatuses.
Referring to FIG. 10A, the background formatting technique described above will be described. In a background formatting process, recording of dummy data is performed in units of predetermined recording blocks BFs sequentially from the innermost radius side of the data area toward the outer radius side, in accordance with the sequence in which user data is recorded.
Now, it is assumed, as shown in FIG. 10A, that background formatting has been carried out sequentially from a block BF 1, located at innermost radius side of the data area, through a block BF 5. Then, recording of a data file is performed similarly to the case illustrated in FIG. 9, in which the user data block UD 1 and the user data block UD 2 are recorded in the data area.
This brings about a condition where, as shown in FIG. 10B, a dummy data block is recorded in the region between the user data blocks UD 1 and UD 2, since the background formatting has been carried out. Under this condition, when a request for disc ejection accompanied by a request for the disc to be made compatible with reproduction-only apparatuses is made, a temporary lead-out is provided at the outer radius region subsequent to the end of the user data block UD 2, i.e., the end position of the user data-recorded region in the data area. This operation facilitates fast disc ejection.
As can be found from the foregoing, performing the background formatting can eliminate or reduce the portion in which dummy data is to be recorded when the disc is ejected. This therefore shortens user waiting time for disc ejection.
Currently, a type of DVD+RW disc which has only one recording layer has been introduced. However, an attempt has been made to develop a multilayered DVD+RW disc, similarly to other types of medium such as a DVD-ROM disc, and a DVD-R or DVD+R disc.
Japanese Unexamined Patent Application Publication No. 1999-167725 discloses a technique for providing a DVD-ROM disc having multiple recording layers. In Japanese Unexamined Patent Application Publication No. 1999-134799, a technique is discussed in which background formatting is performed on a rewritable optical disc recording medium.